1873.] On determining the best Course for a Ship. 263 



part of the plate in front of the rivet. The amount of that bending 

 stress is approximately estimated, and a rule found for the distance of 

 the rivet-hole from the edge of the plate. When the plate gives way by 

 tearing from rivet-hole to rivet-hole, it is commonly assumed that the 

 stress on the part of the plate between the rivets is a uniformly distri- 

 buted stress. This is shown to be not strictly correct, and the want of 

 uniformity of stress will cause the plate to give way with a lower average 

 intensity of stress than that which corresponds to the ultimate resistance 

 of the plate to tension. How much the plate may be weakened by the 

 want of uniformity in the distribution of the stress it is impossible to 

 calculate. Probably the loss of strength due to this cause is in ductile 

 plates very small ; but it is pointed out that this weakening may account, 

 at least in part, for the apparent loss of strength of the plates at joints 

 as compared with the same plates broken in an imperforated condition. 

 This loss of strength has been hitherto ascribed entirely to injury done to 

 the plate in the punching-process. When the rivet gives way by shear- 

 ing, the stress on the section is also not uniform. In consequence of 

 the great deformation of the rivet before fracture, it is subjected to bend- 

 ing as well as shearing action. The friction between the plates induced 

 by the contraction of the rivets in cooling has been supposed sometimes 

 to add to the apparent resistance of the rivet to shearing. It is shown 

 that a considerable displacement of the plates takes place before ultimate 

 fracture, and that the deformation of the rivets is so great that it can 

 hardly be supposed that they exert any tension, holding the plates 

 together at the moment of fracture. The friction should therefore be 

 entirely neglected in estimating the ultimate resistance of riveted joints ; 

 and this, indeed, has been done by most English writers. 



The question of the resistance to deformation is then discussed, and a 

 limit fixed for the safe intensity of the pressure on the bearing surface 

 of the rivet. 



The practical considerations affecting the diameter of the rivet are then 

 stated ; and joining these to the considerations given above, a series of 

 rules for proportioning riveted joints are drawn up, and some Tables of 

 the proportions of rivets and joints are given. 



11. J' On the Employment of Meteorological Statistics in deter- 

 mining the best Course for a Ship whose Sailing Qualities are 

 known." By Francis Galton,, F.R.S. Received March 13, 

 1873. 



If we desire to estimate which of two alternative passages between 

 the same ports would be performed most quickly on the average of many 

 voyages, no knowledge can be more immediately useful than that of the 

 distance which the ship could accomplish at various points of the routes 



